This invention relates to the washing of containers and cans in large quantities. This invention particularly relates to a method and apparatus which may be utilized in a container or can production line to remove foreign matter from the containers or cans incident to the production thereof.
In the manufacture of cans, it may be desirable to provide a can washing system in the can production line which is capable of handling very large quantities of cans. In a so-called D&I (drawn and ironed) can line, large gaps in the flow of cans will oftentimes occur as when the conveying system of the entire can line is stopped for any of a variety of reasons. Typically, a washing system utilized in such a can line comprises a plurality of washing and rinsing zones including an alkaline washing zone and a deionized water rinsing zone. When the cans stop in the washing system due to the interruption in flow of the cans through the can line, the alkaline washing liquid in the washing zone and the deionized rinsing liquid in one of the rinsing zones are directed at the same cans for an extended period of time. Due to the strength and nature of the alkaline washing liquid and the deionized rinsing liquid, the spraying of the cans with these liquids can result in an etching of the cans. Where the cans comprise tinplate, cans can actually be detinned by the action of the alkaline washing liquid and the deionized rinsing liquid.
In order to eliminate this etching or detinning effect caused by extended periods of contact between the cans and the alkaline washing liquid spray and the deionized rinsing liquid spray, the cans have been conveyed on through the washing system even though the rest of the can line has been stopped. This creates large gaps or voids in the production line which are undesirable in that they create delays once the can line is back in operation. In addition, an accumulating capacity must be provided at the output of the washer system which may in itself be expensive.
In order to prevent the etching or detinning of the cans while at the same time avoiding the large gaps or voids in the can production line, the washing system could be closed down with the rest of the line so that the spray of alkaline washing liquid and the spray of deionized rinsing liquid would not be directed at and make contact with the cans within the washer system. However, this would allow the cans to air dry while they remain in the washer system. Such drying is undesirable since it produces oxidation or rusting of the cans.